ET should at least try to call mpv with the right "--target-prim" parameter based on the video information but I don't know if that's possible.
If that's not possible and you dont want to edit the settings every time, you have 2 choices really:
1. Let ET/mpv configuration as it is and force the color space of your TV to bt.709. SDR video will play fine, Wide gamut HDR video will be downgraded to normal gamut and play "ok"
2. Set "--target-prim=bt.2020" in mpv configuration and your TV color space to bt.2020. Wide gamut HDR video will play fine. SDR video will be "upscalled" to bt.2020 and play ok. ET interface, your desktop and any other players or applications will have wrong color (because they wont be upscalled to bt.2020)
Edit: @Luke, is it possible to call mpv with the right "--target-prim" parameter based on the video information? If that's not possible, is it at least possible to include an option to toggle mpv betweem bt.709 and bt.2020 wide gamut manually?
Edited by stettler, 17 October 2018 - 09:57 AM.